#ifndef JSStack_h
#define JSStack_h
#include "ExecutableAllocator.h"
#include "Register.h"
#include <wtf/Noncopyable.h>
#include <wtf/PageReservation.h>
#include <wtf/VMTags.h>
#if !defined(NDEBUG) && !defined(ENABLE_DEBUG_JSSTACK)
#define ENABLE_DEBUG_JSSTACK 1
#endif
namespace JSC {
class ConservativeRoots;
class DFGCodeBlocks;
class ExecState;
class JITStubRoutineSet;
class VM;
class LLIntOffsetsExtractor;
class JSStack {
WTF_MAKE_NONCOPYABLE(JSStack);
public:
enum CallFrameHeaderEntry {
CallFrameHeaderSize = 6,
ArgumentCount = -6,
CallerFrame = -5,
Callee = -4,
ScopeChain = -3,
ReturnPC = -2, CodeBlock = -1,
};
static const size_t defaultCapacity = 512 * 1024;
static const size_t commitSize = 16 * 1024;
static const ptrdiff_t maxExcessCapacity = 8 * 1024;
JSStack(VM&, size_t capacity = defaultCapacity);
~JSStack();
void gatherConservativeRoots(ConservativeRoots&);
void gatherConservativeRoots(ConservativeRoots&, JITStubRoutineSet&, DFGCodeBlocks&);
Register* begin() const { return static_cast<Register*>(m_reservation.base()); }
Register* end() const { return m_end; }
size_t size() const { return end() - begin(); }
bool grow(Register*);
static size_t committedByteCount();
static void initializeThreading();
Register* const * addressOfEnd() const
{
return &m_end;
}
Register* getTopOfFrame(CallFrame*);
Register* getStartOfFrame(CallFrame*);
Register* getTopOfStack();
CallFrame* pushFrame(CallFrame* callerFrame, class CodeBlock*,
JSScope*, int argsCount, JSObject* callee);
void popFrame(CallFrame*);
void enableErrorStackReserve();
void disableErrorStackReserve();
#if ENABLE(DEBUG_JSSTACK)
void installFence(CallFrame*, const char *function = "", int lineNo = 0);
void validateFence(CallFrame*, const char *function = "", int lineNo = 0);
static const int FenceSize = 4;
#else // !ENABLE(DEBUG_JSSTACK)
void installFence(CallFrame*, const char* = "", int = 0) { }
void validateFence(CallFrame*, const char* = "", int = 0) { }
#endif // !ENABLE(DEBUG_JSSTACK)
private:
Register* reservationEnd() const
{
char* base = static_cast<char*>(m_reservation.base());
char* reservationEnd = base + m_reservation.size();
return reinterpret_cast_ptr<Register*>(reservationEnd);
}
#if ENABLE(DEBUG_JSSTACK)
static JSValue generateFenceValue(size_t argIndex);
void installTrapsAfterFrame(CallFrame*);
#else
void installTrapsAfterFrame(CallFrame*) { }
#endif
bool growSlowCase(Register*);
void shrink(Register*);
void releaseExcessCapacity();
void addToCommittedByteCount(long);
Register* m_end;
Register* m_commitEnd;
Register* m_useableEnd;
PageReservation m_reservation;
CallFrame*& m_topCallFrame;
friend class LLIntOffsetsExtractor;
};
inline void JSStack::shrink(Register* newEnd)
{
if (newEnd >= m_end)
return;
m_end = newEnd;
if (m_end == m_reservation.base() && (m_commitEnd - begin()) >= maxExcessCapacity)
releaseExcessCapacity();
}
inline bool JSStack::grow(Register* newEnd)
{
if (newEnd <= m_end)
return true;
return growSlowCase(newEnd);
}
}
#endif // JSStack_h